Medical tubes are used in a variety of medical procedures that require one end of the tube to be located inside the body while the other end remains outside the body. Such tubes can be useful in treating a patient over an extended period of time by, for example, repeated administration of medication, delivery of nutrients or oxygen, or removal of fluids. Proper placement and positioning of medical tubes is often critical to their effective use. For example, it is typically desirable to administer medication or deliver nutrients to a specific location in the body to maximize the efficacy of the medication or the benefits of the tube. However, placement of most medical tubes is often performed without immediate visual confirmation that the tube has been located at the proper location.
For example, medical tubes are often used to treat a patient if the patient has a compromised ability to obtain proper nutrition through oral intake. The medical tubes used for this treatment are more commonly referred to as nasogastric or nasoenteric feeding tubes. Placement of these feeding tubes is routinely performed in a number of clinical settings including emergency rooms, hospital wards and intensive care units totaling greater than 1.2 million tubes annually. Feeding tube placement, like placement of most other medical tubes, is commonly done without a visual aid to help medical personnel navigate the tube down the nose, through the esophagus and into the stomach or small intestine and confirm that the distal end of the tube is placed in its proper end location. Medical personnel advance the tubes through the patient's body blindly. Because the medical personnel cannot see the distal end of the feeding tube during advancement, the feeding tube can be incorrectly positioned during the process. In extreme cases, the distal end of the feeding tube may pass into the cranium and into the patient's brain, while the nurse or other practitioner continues advancing the feeding tube believing that it is properly entering the gastrointestinal tract.
More commonly, misplacement of the feeding tube results in other serious complications including lung placement or puncture or esophageal puncture. It is estimated that 3.2 percent of all blind nasoenteric feeding tube placements result in the feeding tube being disposed in the lung. In approximately 1.2 percent of placements, the patient will suffer a punctured lung. In approximately 0.5 percent of cases, the patient will die as a result of the procedure. It is estimated that in intensive care units alone, up to six thousand patients die each year from improperly placed feeding tubes.
Additionally, providing any feeding solution through the feeding tube into the lungs likely results in pneumonia with increased morbidity and mortality. Thus, it is critical to ensure verify that there has been proper placement of the feeding tube. Unfortunately, many common methods for doing so leave patients at substantial risk.
Proper placement of the tube is verified using a variety of tests, including chest x-ray, pH tests, auscultation, or fluoroscopy. However, these tests only attempt to confirm position after placement when complications may have already occurred. For example, if fluoroscopy or X-ray confirms that the feeding tube is actually disposed in the lung, it does so only after the possibility of lung puncture or other damage to the lung tissue. Additionally, while X-ray imaging and fluoroscopy are often used, both only provide a two dimensional indication of location, i.e. placement below the diaphragm. In multiple instances, confirmation of placement has been given when the feeding tube had actually passed through the lung and along the diaphragm, rather than being disposed in the gastrointestinal tract. Moreover, X-ray or fluoroscopic confirmation does not clearly confirm placement in the small bowel rather than the stomach. Small bowel placement is generally preferred to prevent the risk of aspirating feeding solution.
Additionally, some of these techniques have additional limitations and drawbacks. For example, fluoroscopic exams and X-Ray verification can cost $400 or more and can expose the patient and the practitioner to harmful radiation. If a patient is pregnant, a child or in poor health, exposure to such radiation may be highly undesirable. Additionally, the use of such verification procedures significantly prolongs the period of time that a patient must wait after a feeding tube is placed before feeding can begin. Because of this, the average time from ordering feeding tube placement to confirmation of placement and beginning of feeding is 22-26 hours. If the tube is placed improperly, the wait to begin feeding can take even longer as the process must be repeated. During this time, the patient is unable to obtain nourishment and any medications which may be delivered via a feeding tube.
Another complication which is common with patients receiving a feeding tube is that the patients are often not coherent. The patient may be partially sedated or may be delirious. Thus, it is not uncommon for a patient to pull out a feeding tube which has previously been placed. This requires repetition of the procedure, again subjecting the patients to the risks set forth above. Thus, a simpler, safer method for placing feeding tubes would be highly desirable.
An alternate method for placement and verification of feeding tubes is by use of an endoscope. Typically an endoscope is inserted into the mouth of the patient and advanced down until the endoscope has passed through the esophagus and at least into the stomach, and preferably through the pyloric sphincter and into the duodenum. In some applications, a guidewire is advanced to the proper location and the endoscope is removed. The guidewire is then manipulated to move it from the oral placement to a nasal placement, and a feeding tube is advanced along the guidewire into the desired location.
In other applications, the feeding tube is carried in a working channel (or along the side) of the endoscope. The feeding tube is sufficiently long that once the feeding tube has been placed, the endoscope can be removed over the feeding tube. The feeding tube is then cut and an appropriate adaptor attached for feeding.
While placement and verification using an endoscope is advantageous, it also has several drawbacks. One drawback is that using an endoscope usually takes considerable skill to steer the tip of the endoscope through complex and tortuous paths in the body, which can be made more difficult if the tip cannot be steered in multiple directions. Furthermore, endoscopy procedures are typically performed by physicians, often requiring a longer wait time before a properly trained physician is available to place the feeding tube, as opposed to the wait time if medical personnel other than a physician could place the tube.
Another drawback of using an endoscope to place a feeding tube is that, because the endoscope is typically placed through the mouth, an additional procedure must be used if the feeding tube is to be used nasoenterically. This involves advancing a structure through the nose and out the mouth, securing the end of the feeding tube (or a guidewire) to the structure, and then pulling the structure and the end of the feeding tube through the nose. Also, the procedure usually requires conscious sedation which increases the risk and cost of the procedure.
Additionally, an endoscope is a complex, expensive medical device. One significant cost associated with the manufacture of an endoscope can be the optical fibers used to transmit light and images. Devices that are designed to inspect the inside of the body of a human or animal are typically designed to allow medical personnel to perform additional functions inside the patient, other than just viewing the internal anatomy. Additionally, these devices must be able to navigate through narrow passageways in the body. Thus an optical fiber that is appropriate for use in such devices must be sufficiently narrow so that the device and any additional lumen for passing instruments, wires, etc., can comfortably traverse through narrow passageways in the body. Optical fiber with a small enough diameter, however, is typically more expensive. For example, the cost of an optical fiber made essentially of glass (1.0 OD) can be more than four times greater than the cost of an optical fiber made of plastic (1.8-2.0 OD) which performs similarly as the smaller, glass optical fiber. The larger optical diameter of the cheaper, plastic optical fiber, however, may limit the amount of space for additional lumens that may be used to perform additional functions.
Furthermore, because an endoscope is a complex and expensive medical device it is generally not discarded after use in one patient, but rather it is reused in subsequent patients. Prior to reuse of the endoscope, however, it must be properly prepared and sterilized to reduce the risk that an infection could be transmitted from one patient to another. The procedure of cleaning and disinfecting an endoscope is both time consuming and expensive and may involve mechanical cleaning, leakage testing, disinfecting the endoscope chemically for an appropriate amount of time, and then rinsing and drying the endoscope. Often this process must be accomplished by an individual properly qualified to perform the procedure.
Each of the above-referenced methods for placing a feeding tube also has problems with subsequently confirming that the feeding tube remains properly placed. As a patient moves, the distal end of the feeding tube can work its way out of the intestine and coil in the stomach. Depending on the particular concerns regarding the patient, it may be necessary to periodically confirm that the feeding tube is placed properly. This can require additional x-ray, pH tests, auscultation, or fluoroscopy, or the use of another endoscope to ensure that the feeding tube is properly placed. Each of these methods for confirming placement has the drawbacks mentioned above.
Although the current discussion has been directed at the disadvantages of current methods for placing a feeding tube, similar disadvantages exist with current procedures for placing other medical tubes. Such other procedures include placement of a jejunal extension tube in percutaneous gastrojejunal feeding tubes (PEGJ). Presently, for PEGJ tubes, the jejunal extension tube must be threaded through the existing gastrostomy tube or stoma into the small bowel. This is done using fluoroscopy or endoscopy to advance a wire into the small intestine and then a jejunal feeding tube is passed over the wire into the small intestine (jejunum). A jejunal extension tube with direct visualization and/or steering mechanism could perform the same task without the drawbacks of using endoscopy or fluoroscopy as noted previously.
Other situations include those in which prolonged visualization and access for irrigation/infusion and drainage would be beneficial. For example, in pancreatobiliary infections, it is not uncommon for the common bile duct (or associated duct) to become blocked and restrict fluid flow into the duodenum. An endoscope or other catheter based method is typically used to place a shunt or stent in the pancreatic duct or the common bile duct to allow proper drainage of pus from the pancreatobiliary ducts through the common bile duct into the duodenum. Once the situation has been alleviated, an endoscope or other device may be advanced back into the duodenum to remove the shunt or stent. Of course, it is often difficult to tell if the situation has been fully alleviated, if the device has become misplaced, or if the symptoms have simply been reduced.
In these procedures, as well as others in the body, it may be advantageous to provide continued viewing capacity both to ensure proper placement of the structure used for drainage, and to allow medical personnel to get a view of the affected area to determine whether and how quickly healing and/or drainage is taking place. In these clinical situations such a device can replace or assist fluoroscopy and/or endoscopy for guidance, placement, confirmation and reconfirmation. In addition, such an indwelling device can be used to drain pus or other bodily fluids from body cavities as well as provide a conduit for irrigation and infusion of medications including antibiotics.
Accordingly, it would be desirable to provide a medical tube which can be placed more conveniently and which can be used to confirm placement without the need for radiation or other traditional confirmation methods. Additionally, it would be advantageous if such medical tubes could be used, and methods for placing such medical tubes could be performed, by medical personnel other than physicians.
Thus, there is a need for an improved optically guided medical tube and control unit assembly and methods of using the same that reduces risks associated with the placement of medical tubes inside the body of a patient. The improved optically guided medical tube and control unit assembly should be readily reusable to confirm that the distal end of a medical tube has not been displaced after the medical tube has been associated with a patient over an extended period of time, for example about 30 minutes or more. It is desirable that the optically guided medical tube and control unit assembly is relatively easy to use and that it is relatively inexpensive to manufacture.